IndVarSimplify sometimes makes transforms basing on users that are trivially dead. In particular,
if DCE wasn't run before it, there may be a dead `sext/zext` in loop that will trigger widening
transforms, however it makes no sense to do it.
This patch teaches IndVarsSimplify ignore the mist trivial cases of that.
Differential Revision: https://reviews.llvm.org/D47974
Reviewed By: sanjoy
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334567 91177308-0d34-0410-b5e6-96231b3b80d8
The patch was reverted due to a bug. The bug was that if the IV is the 2nd operand of the icmp
instruction, then the "Pred" variable gets swapped and differs from the instruction's predicate.
In this patch we use the original predicate to do the transformation.
Also added a test case that exercises this situation.
Differentian Revision: https://reviews.llvm.org/D35107
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307477 91177308-0d34-0410-b5e6-96231b3b80d8
It appears that the problem is still there. Needs more analysis to understand why
SaturatedMultiply test fails.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307249 91177308-0d34-0410-b5e6-96231b3b80d8
It seems that the patch was reverted by mistake. Clang testing showed failure of the
MathExtras.SaturatingMultiply test, however I was unable to reproduce the issue on the
fresh code base and was able to confirm that the transformation introduced by the change
does not happen in the said test. This gives a strong confidence that the actual reason of
the failure of the initial patch was somewhere else, and that problem now seems to be
fixed. Re-submitting the change to confirm that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307244 91177308-0d34-0410-b5e6-96231b3b80d8
-If there is a IndVar which is known to be non-negative, and there is a value which is also non-negative,
then signed and unsigned comparisons between them produce the same result. Both of those can be
seen in the same loop. To allow other optimizations to simplify them, we turn all instructions like
%c = icmp slt i32 %iv, %b
to
%c = icmp ult i32 %iv, %b
if both %iv and %b are known to be non-negative.
Differential Revision: https://reviews.llvm.org/D34979
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307126 91177308-0d34-0410-b5e6-96231b3b80d8
We can use calls to @llvm.experimental.guard to prove predicates,
relying on the fact that in all locations domianted by a call to
@llvm.experimental.guard the predicate it is guarding is known to be
true.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268997 91177308-0d34-0410-b5e6-96231b3b80d8
